#he just cannot kill people directly which is crucial to understanding his character esp as he relates to aang and katara

[comradekatara]

You've mentioned Zuko's "inability to kill" before, so could I ask you to elaborate on that?

sure. zuko is banished for, essentially, committing treason. he says to ozai that he was banished for "speaking out of turn," but simply speaking out of turn is not actually why ozai banished him. zuko said that people shoudn't have to die for the sake of further empowering the fire nation, and that goes against their nation's entire ethos. zuko lacks, as azula puts it, that "killer instinct that is just so fire nation."

while zuko does set fire to suki's village in his quest to capture aang, and you could argue that he may have committed other such acts offscreen, we never actually see him outright kill anyone. unlike zhao, who kills the moon, and azula, who kills aang in a manner that would have ended the entire avatar line had katara not revived him, zuko threatens and intimidates and harms, but when it comes down to it, he does not actually kill, because he simply cannot.

he threatens to kill zhao, and if he had killed zhao, no one in the audience would fault him for it. zuko does not even burn him upon winning their agni kai, going against custom; zhao calls him a coward for it. zhao tries to kill zuko on multiple occasions, including when he blows up zuko's entire ship. but, when the ocean spirit is dragging zhao under, zuko still extends his hand in a futile attempt to save zhao. contrast this scene with sokka arguing to leave zuko for dead in the same episode. he legitimately does not have a problem with letting zuko die, because, as he says, zuko would do the same thing to them (at least, sokka seems to think so).

sokka kills combustion man, toph kills yu and xin fu, and neither of them have any regrets. conversely, katara cannot kill yon rha, and aang cannot kill ozai. like sokka and toph, they are justified in killing these men, perhaps even more so (since yin and xin fu did not actually attempt to kill toph, "only" kidnap her), but they ultimately choose mercy. like zuko on kyoshi island, aang and katara's actions, such as blowing up the factory in jang hui, may have had indirect casualties (i don't count aang being merged with the ocean spirit because he was not truly in control), but they are never able to kill directly, because when faced with another human being, regardless of how much they may hate them, their pathos prevents them from delivering that killing blow.

zuko, as a foil to aang and katara and the deuteragonist of the narrative, is also someone whose instincts prevent him from being the cold-blooded killer his nation expects of him. it is why, unlike the rest of his family (including iroh), he is unable to produce lightning; he is too sensitive to become the perfect weapon his father wants him to be, which is why azula's reveal is so thrilling and terrifying to the audience, because she is what ozai wants in a protege, unlike zuko, who try as he might, fails at embodying the fire nation values of ruthlessness and power at any cost.